Successful Use of Mixed Aluminum-Steel Drill Pipe String in Complex Horizontal Wells: Case Study

Abstract High strength-to-weight aluminum alloy drill pipe is a powerful torque and drag reduction tool for deviated wells. The aluminum alloy drill pipe enables to achieve strength to weigh ratios equivalent to 160 ksi yield strength steels and is typical 30-50% lighter than similar steel drill pipe. An operator has recently tested aluminum alloy drill pipe in a complex and highly deviated well profile. This paper presents the key findings regarding the benefits of drilling using aluminum drill pipes in a mixed aluminum-steel string compared to a string using steel pipes only. Firstly, the innovative drill pipe design is presented, followed by lessons learned during rig operations regarding pipe handling practices, rig compatibility and pipe inspection. Then, the paper presents results of an advanced torque, drag and buckling simulations taking into account the rigorous mechanical characteristics of aluminum drill pipe. In well planning phase, sensitivity analysis enabled to optimize the placement of aluminum drill pipe along the mixed aluminum-steel drill string according to the well profile and to predict anticipated torque, drag and loads on pipes while drilling. Through extensive modeling and field data interpretation, the paper presents a comparison of the overall drilling performances between steel only and aluminum-steel drill pipe string, and provides metrics in terms of torque and drag reduction. These results were then used to challenge horizontal and extended reach drilling well profiles where the utilization of steel drill pipes only has shown its limitation.